U.S. patent number 4,359,228 [Application Number 06/273,096] was granted by the patent office on 1982-11-16 for linecutter seal, apparatus and method.
This patent grant is currently assigned to Garlock Inc.. Invention is credited to Douglas A. Cather.
United States Patent |
4,359,228 |
Cather |
November 16, 1982 |
Linecutter seal, apparatus and method
Abstract
A linecutter article, apparatus and method wherein the
linecutter is mounted adjacent a shaft seal cutting line to protect
the shaft seal(s). The linecutter includes an annular ring of
tough, low coefficient of fricton, abrasion-resistant, ultra-high
molecular weight polyethylene or its equivalent in contact with the
shaft and having a sharp linecutter edge facing outwardly. The ring
is tough enough to cut monofilament fishing line but flexible
enough to follow shaft runout and provides an additional seal.
Inventors: |
Cather; Douglas A. (Gastonia,
NC) |
Assignee: |
Garlock Inc. (Longview,
TX)
|
Family
ID: |
23042543 |
Appl.
No.: |
06/273,096 |
Filed: |
June 12, 1981 |
Current U.S.
Class: |
277/550; 277/309;
277/551; 277/560; 277/565; 277/944 |
Current CPC
Class: |
B63H
5/165 (20130101); F16J 15/3204 (20130101); F16J
15/002 (20130101); Y10S 277/944 (20130101) |
Current International
Class: |
B63H
5/00 (20060101); B63H 5/16 (20060101); F16J
15/00 (20060101); F16J 15/32 (20060101); F16J
015/54 () |
Field of
Search: |
;277/1,32,11,237R,DIG.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith; Robert I.
Claims
I claim:
1. A linecutter seal comprising:
(a) an annular metal shell including a cylindrical portion and a
radial flange extending radially inwardly from the axially inner
end of said cylindrical portion, said cylindrical portion having an
outside diameter adapted to press-fit in a housing bore;
(b) a molded elastomeric body bonded to said cylindrical portion
and to said radial flange, said body being located radially
inwardly of said cylindrical portion and axially outwardly from
said radial flange; and
(c) an annular ring of tough, low coefficient of friction,
abrasion-resistant material tough enough to cut nylon fishing line,
said ring being bonded to the radially inner generally cylindrical
surface of said elastomeric body, said ring having an annular
inside diameter shaft contacting surface that in its free, formed
shape, tapers radially inwardly and axially outwardly, said ring
also having an axially outer radial surface that forms an acute
angle with said annular inside diameter surface, said shaft
contacting surface and said radial surface of said ring meeting at
a sharp linecutter edge.
2. The seal as recited in claim 1 wherein said ring material is
ultra-high molecular weight polyethylene.
3. The seal as recited in claim 2 wherein said acute angle is in
the range of from about 30.degree. to 70 .degree..
4. The seal as recited in claim 2 wherein said shaft contacting
surface is at an angle of about 10.degree. to the axis of said
seal.
5. The seal as recited in claim 2 wherein said body has an axially
outer radial surface having a radially outer radial portion
positioned axially outwardly of said linecutter edge, a radially
inner tapered portion in-line with said radial surface of said
ring, and a substantially cylindrical portion joining said radial
portion and said tapered portion.
6. The seal as recited in claim 1 wherein said acute angle is
approximately 50.degree..
7. The seal as recited in claim 6 wherein said ring material is
ultra-high molecular weight polyethylene.
8. The seal as recited in claim 7 wherein said shaft contacting
surface is at an angle of about 10.degree. to the axis of said
seal.
9. Apparatus comprising:
(a) a shaft, a housing having a bore, defined by a bore wall,
through which bore said shaft extends and an annular space between
said bore wall and said shaft;
(b) a shaft seal located in said annular space for sealing said
space against the passage of fluids therethrough; and
(c) a linecutter seal located in said space axially outwardly from
said shaft seal, and comprising an annular ring of tough, low
coefficient of friction abrasion-resistant material tough enough to
cut nylon fishing line, having an annular inside diameter shaft
contacting surface in contact with said shaft, said ring having an
axially outer radial surface that forms an acute angle with said
annular inside diameter surface of said ring, said annular inside
diameter surface and said radial surface of said ring meeting at a
sharp linecutter edge.
10. The apparatus as recited in claim 9 wherein said ring material
is ultra-high molecular weight polyethylene.
11. The apparatus as recited in claim 10 wherein said acute angle
is in the range of from about 30.degree. to 70.degree..
12. The apparatus as recited in claim 10 wherein said body has an
axially outer radial surface having a radially outer radial portion
positioned axially outwardly of said linecutter edge, a radially
inner tapered portion in-line with said radial surface of said
ring, and a substantially cylindrical portion joining said radial
portion and said tapered portion.
13. The apparatus as recited in claim 9 wherein said acute angle is
approximately 50.degree..
14. The apparatus as recited in claim 13 wherein said ring material
is ultra-high molecular weight polyethylene.
15. The apparatus as recited in claim 13 wherein said body has an
axially outer radial surface having a radially outer radial portion
positioned axially outwardly of said linecutter edge, a radially
inner tapered portion in-line with said radial surface of said
ring, and a substantially cylindrical portion joining said radial
portion and said tapered portion.
16. The apparatus as recited in claim 9 wherein said linecutter
seal includes:
(a) an annular metal shell including a cylindrical portion and a
radial flange extending radially inwardly from the axially inner
end of said cylindrical portion, said cylindrical portion having an
outside diameter that is a press-fit in said bore wall,
(b) a molded elastomeric body bonded to said cylindrical portion
and to said radial flange, said body being located radially
inwardly of said cylindrical portion and axially outwardly from
said radial flange; and wherein
(c) said ring is bonded to the radially inner surface of said
elastomeric body, said annular inside diameter surface of said
ring, in its free, as-formed shaped, tapering radially inwardly and
axially outwardly.
17. The apparatus as recited in claim 16 wherein said ring material
is ultra-high molecular weight polyethylene.
18. The apparatus as recited in claim 17 wherein said acute angle
is in the range of from about 30.degree. to 70.degree..
19. The apparatus as recited in claim 18 wherein said acute angle
is approximately 50.degree..
20. A method for protecting a shaft seal of a shaft extending
through a bore defined by a bore wall in a housing comprising
mounting, in said wall of said housing bore axially outwardly from
said shaft seal, a linecutter seal including an annular ring of
tough, low coefficient of friction, abrasion-resistant material
tough enough to cut nylon fishing line, and having an annular
inside diameter shaft contacting surface in contact with said
shaft, said ring having an axially outer radial surface that forms
an acute angle with said annular inside diameter surface of said
ring, said annular inside diameter surface and said radial surface
of said ring meeting at a sharp linecutter edge.
21. The method as recited in claim 20 wherein said ring material is
ultra-high molecular weight polyethylene.
22. The method as recited in claim 21 wherein said acute angle is
in the range of from about 30.degree. to 70.degree..
23. The method as recited in claim 22 including positioning said
radial surface of said ring at an acute angle of about 50.degree.
to the surface of said shaft.
24. The method as recited in claim 21 including bonding said ring
to an elastomeric body positioned radially outwardly of said ring
for providing a resilient force urging said linecutter edge into
contact with said shaft.
Description
TECHNICAL FIELD
This invention relates to linecutters and in one embodiment to
linecutters mounted adjacent propshaft seals of small marine
engines for cutting nylon fishing line to protect the propshaft
seal(s).
BACKGROUND
It is current practice to use a formed metal linecutter adjacent
the propshaft of small marine engines such as outboards, inboards
and inboard-outboards, used for fishing. The purpose of the
linecutter is to protect the propshaft seal(s) from nylon fishing
line which may wrap around the propshaft. The inner diameter of the
linecutter must be ground for two reasons: (1) to produce a sharp
outward-facing edge to cut fishing line, and (2) to achieve a
minimal shaft clearance with an exceptionally tight tolerance
(.+-.0.0005-0.0010 inches).
The linecutter shell is usually cup-shaped and the outer propshaft
seal is pressed into it to form a seal-linecutter assembly.
Therefore, the inside diameter-outside diameter concentricity of
the metal linecutter must be held to 0.005 inch TIR (total
indicator reading) or less. The major disadvantages of such known
linecutters are cost, grooving of the shaft due to shaft runout,
and generation of heat near the seal.
SUMMARY OF THE INVENTION
A linecutter seal, apparatus and method including an annular ring
of tough, abrasion resistant, ultra-high molecular weight
polyethylene or its equivalent, having an annular inside diameter
shaft-contacting surface and an axially outer radial surface that
meets the shaft-contacting surface at an acute angle forming a
sharp linecutter edge riding on the shaft. The polyethylene ring is
tough enough to cut nylon monofilament fishline, yet is preferably
flexible enough to follow shaft runout and is non-abrasive thus
virtually eliminating grooving of the shaft. Because of its
flexibility and low abrasiveness, the polyethylene ring is designed
with shaft interference eliminating the need for the tight
tolerances needed on the prior art ground metal linecutter, and
also producing an additional sealing effect on the shaft axially
outside of the primary seal(s).
The polyethylene ring is preferably part of a molded unit including
a metal shell and an elastomeric body with the ring being a liner
on the inside diameter of the elastomeric body.
It is an object of the present invention to provide a linecutter
seal, apparatus, and method that eliminates the above-mentioned
problems in the prior art.
It is another object of the invention to provide a linecutter that
eliminates shaft grooving, that does not overheat adjacent the
propshaft seal(s), that is less expensive in eliminating a grinding
operation and the need for tight tolerances and concentricity, and
that, at the same time, provides an additional sealing effect on
the shaft outside of the primary seal(s).
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be more fully understood by reference to
the following detailed description thereof, when read in
conjunction with the attached drawings, wherein like reference
numerals refer to like elements and wherein:
FIG. 1 is a partial cross-sectional view through a prior art
linecutter;
FIG. 2 is a partial cross-sectional view showing the linecutter of
the present invention in combination with a marine engine housing,
shaft and primary seals; and
FIG. 3 is an enlarged partial cross-sectional view of the
linecutter of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
With reference now to the drawings, FIG. 1 shows a known linecutter
and seal arrangement including a marine engine housing 10, a shaft
12, a bearing 14, a propshaft seal 16, and a metal linecutter 18
having a cutting edge 20. The linecutter 18 is cup-shaped and the
propshaft seal 16 is pressed into the linecutter and held by a
crimped edge 22. The inside diameter surface 24 of the linecutter
is ground to produce the sharp edge 20 and to achieve a minimal
shaft clearance with an exceptionally tight tolerance of about
.+-.0.0005-0.0010 inch.
FIG. 2 shows a linecutter 30 according to the present invention,
installed in a marine engine housing 32 having a bore 34, defined
by a bore wall 36, through which bore a propshaft 38 extends, a
bearing 40, a propshaft seal 42 and the linecutter 30.
The linecutter 30 has an inside diameter shaft-contacting surface
44 and a cutting edge 46 in contact with the shaft. FIG. 2 also
shows, in dotted lines, the as-molded shape of the linecutter 30,
showing that the linecutter is designed with a certain amount of
interference with the shaft. As shown in FIG. 2, both the seal 42
and the linecutter 30 form a press-fit with the bore wall 36.
For purposes of the present specification and claims, the term
"axially inner" means the oil side, or to the left in FIGS. 1-3,
and "axially outer" means the water side or to the right in FIGS
1-3.
Referring now to FIG. 3, the linecutter 30 includes an annular
metal shell 48, a molded elastomeric body 50 and a liner or ring 52
of ultra high molecular weight polyethylene. The linecutter 30 is
preferably made by a known molding process (as will be understood
by anyone skilled in the art) in which all three of the shell,
elastomeric preform, and ring are placed in a mold cavity; the mold
is then closed molding the body to the desired shape from the
preform, forming the ring to the desired shape from a flat ring
tube or washer, and bonding the three parts together.
The shell 48 includes a cylindrical portion 54 and a radial flange
56 extending radially inwardly from the axially inner end of the
cylindrical portion. The outside diameter surface of the
cylindrical portion 54 is designed and adapted to form a press-fit
in the bore wall 36. The shell is preferably type 302/304
stainless, and in one embodiment is 0.030 inches thick (#22 gauge),
having a pierce of about 0.655 inches and a width of 0.128
inches.
The molded elastomeric body 50 is bonded to the cylindrical portion
54 and to the radial flange 56 and is located radially inwardly of
the cylindrical portion and axially outwardly of the radial flange.
The body 50 has an axially outer radial surface 58 including a
radially outer radial portion 60, a radially inner tapered portion
62, and a cylindrical portion 64. The radial surface 58 thus has an
outwardly facing groove 59 which provides a desired amount of
flexibility to the ring 52. The radial surface 58 is located
axially outwardly of the edge 46 in their as-molded shape. The
preferred elastomer is nitrile.
The liner or ring 52 is bonded to the radially inner, generally
cylindrical surface of the elastomeric body. The ring 52 includes
an axially outer radial surface 66 that forms an acute angle with
the annular inside diameter shaft-contacting surface 44 thus
forming the sharp linecutter edge 46. The sharp cutting edge 46 can
be formed during molding via pinchoff, or it can be trimmed after
molded. Preferably it is formed by pinchoff during molding. The
ring 52 is formed to its desired shape during molding. The acute
angle is most preferably about 50.degree., however, it can be any
acute angle less than 90.degree., but preferably is in the range of
from about 30.degree.-70.degree.. The ring 52 is preferably made of
an ultra-high molecular weight polyethylene. The ring 52 must be
tough enough to cut nylon fishing line, abrasion resistant and is
also preferably flexible enough to follow shaft runout. While
ultra-high molecular weight (2,000,000 to 6,000,000) polyethylene
(see pages 66-68 of "Modern Plastics Encyclopedia", 1980-81 Edition
(McGraw-Hill, New York, 1980) is preferred, other equivalent tough,
low coefficient of friction, abrasion-resistant materials can be
used including various plastics, such as glass-filled nylon.
In the as-molded shape of the linecutter 30, the inside diameter
surface 44 makes an acute angle of about 10.degree. to the
linecutter axis, while the radial surface 66 makes an acute angle
of about 60.degree. to the linecutter axis.
In one preferred embodiment, the ring 52 as formed in the mold had
an interference of about 0.010 inch with the shaft 38, which had a
diameter of 0.6245 inch. The linecutter 30 outside diameter was
1.128 inch, the axial length of the linecutter was 0.143 inch, the
radial clearance between the shaft and the axially inner end of the
inside diameter surface 44 of the ring 52 was 0.005 inch, and the
axially inner end of the ring 52 was cylindrical for 0.045 inches
before it started to taper radially inwardly toward the shaft. The
axial length of the linecutter was 0.130 inches. The radial
distance from the shaft to the cylindrical portion 64 of the
surface 58 was 0.100 inch.
The invention has been described in detail with particular
reference to the preferred embodiments thereof, but it will be
understood that variations and modifications can be affected within
the spirit and scope of the invention as described hereinafter and
as defined in the appended claims. For example, the linecutter 30
can be used in other assemblies than that shown in FIG. 2, and with
other types of seals. One such example would be an apparatus in
which the linecutter also performs a principal sealing function and
the axially outwardly facing lip of FIG. 2 is omitted. Further, the
linecutter and the seal may be united within a unitary structure.
Such a unitary structure can be made with a separate unifying shell
or by an extension of the shell of the seal or the shell of the
linecutter to retain both members. Further, other shapes for the
shell 48 and the body 50 can be used, and in fact one or both of
these can be omitted with other means substituted therefore for
holding the ring 52 in place. The linecutter 30, is, of course, not
limited in use to cutting fishing line and is not limited to use in
marine engines. For example, this invention can be applied in a
disk harrow to exclude "lines" such as cornstalks or vines. The
term "line" is defined for use in the present specification and
claims as meaning any of various elongated materials that might
tend to wrap around a shaft, such as and including fishing line,
grass, cornstalks, vines and the like.
* * * * *